Modern vehicles are equipped with numerous devices and systems that require electrical power from a vehicle power supply, typically a battery. Power (and increasingly, information) is commonly routed to those devices and systems through a wire harness comprising bundled conductors that snake through the vehicle's interior, branching as needed to reach each device and system requiring power. Wire harnesses must be securely fastened along their lengths, for support, to maintain clearance from hazards, and to eliminate rattle. The typical fastening technique is to first secure fasteners to the wire harness at predetermined intervals intended to match mounting holes, brackets, tape supports, and other convenient mounting points in the vehicle's interior, and then to install the fastener-equipped harness.
Because the dimensions of individual wire harnesses and the locations of corresponding mounting points and electrical systems in any given vehicle naturally vary, wire harnesses always include a certain amount of extra length or tolerance estimated for a given installation. Too little, and the harness isn't long enough to be connected properly; too much, and the cost and weight of the wire harness are unnecessarily increased, and installation is complicated by the need to secure the excess harness in a manner preventing rattle and contact with known hazards such as sharp edges, moving parts, hot surfaces, and others. This built-in extra length, while necessary, complicates the pre-placement of fasteners on the harness with proper tolerances between them for all of the fastener mounting points over the total length or “run” of the harness in the vehicle.
The usual prior art method for determining the optimal position for each fastener on a wire harness, which will be called “cumulative tolerancing”, bases the location of each fastener from a single, fixed point of reference on the harness, usually from one end. The distance from each fastener to the reference point is assigned a given tolerance, i.e. the tolerances are length-specific according to a table or chart. These length-specific tolerances are added to the length of the wire harness, but the cumulative nature of the tolerances makes fastener placement confusing and difficult.